1. Field of the Invention
The present invention relates to method for correcting a static posture of a head portion and a static posture correcting apparatus for a head suspension and the like for a hard disk drive incorporated in an information processing apparatus such as computer.
2. Description of the Related Art
Recently the tolerance of a pitch angle and a roll angle as a static posture angle of a head portion of a head suspension is diminished. A pitch and roll correcting process for correcting a pitch angle and a roll angle of the head portion has become important. The head portion constitutes a flexure to be attached to a head suspension, for supporting a slider to write and read data to and from a disk arranged in a hard disk drive.
In a pitch and roll correcting process according to a related art, for example, a pitch angle and a roll angle of a head portion of a flexure of a head suspension without a slider or a head gimbal assembly with a slider are measured previously. Then irradiation lines are selected to correct the head portion so as to obtain a target pitch angle and a target roll angle thereof, and laser beams are irradiated on the selected irradiation lines in turn. In the specification, the head suspension and the head gimbal assembly are hereinafter referred to as “head suspension.”
The selection of the irradiation lines is, for example, made as follows. Namely, it measures the amount of change of data from a plurality of sample head suspensions which show where and how a flexure is irradiated and how much the angles change at a head portion. It is hereinafter referred to as “calibration.” Based on the results of this calibration, a correction recipe-table covering all the combinations of irradiation lines which shows where to irradiate laser beam to correct a head portion so as to obtain target angles thereof is prepared.
Then a combination of irradiation lines as a correction recipe is selected from the correction recipe-table so as to correct a pitch angle and a roll angle measured from a head portion of a flexure of an objective head suspension before correction into a target pitch angle and a target roll angle with the minimum number of laser irradiation.
The laser irradiation is done on each selected irradiation line of the flexure of the objective head suspension according to the selected correction recipe, so that the pitch angle and the roll angle of the head portion of the flexure of the objective head suspension are corrected.
However, in the correction method with the minimum number of laser irradiation according to the related art, the variations among the sample head suspensions of calibration results are not considered. This generates great variation in a pitch angle and a roll angle due to correction, to deteriorate the correction accuracy.
The related art mentioned above is disclosed in Japanese Unexamined Patent Application Publication No. 2002-74630.